The Kaleme website said that with the attack on Wednesday night, "a new wave of pressure and limitations" on Mousavi had started. It said some of his belongings were taken along with the computers.

Mousavi, who lost to hardline President Mahmoud Ahmadinejad in a disputed election in June 2009, has remained the main leader of the reformist "Green" movement.

Both Mousavi and another opposition figure Mehdi Karoubi say the vote was rigged to secure the re-election of Ahmadinejad but authorities deny the charge, saying it was the healthiest election the country has had.

The vote was followed by street protests, the worst unrest since the Islamic republic was founded in 1979, which were put down violently by security forces. Mass detentions and trials followed. Two people were hanged and scores of detainees remain in jail.

Earlier this month, opposition websites reported that members of the Basij militia loyal to Supreme Leader Ayatollah Ali Khamenei smashed windows and damaged security cameras at the home of Karoubi, injuring one of his bodyguards.

The semi-official Fars news agency quoted Iran's police chief Esmail Ahmadi-Moghaddam as saying on Thursday around 100 people had been indentified after gathering in front of Karoubi's house.

"But the police do not confront people just because they have gathered at a place," he said according to Fars, without referring to the attack on Karoubi's house.

"Karoubi has taken part in many illegal (opposition) rallies himself. He had called on people to be present at these rallies but we have not arrested him," Ahmadi-Moghaddam added.

Mousavi says the reformist movement is alive, but the campaign seems to be fading as many Iranians feel the former prime minister lacks the political courage to confront the establishment from which he sprang.

At least a dozen pro-reform publications and most opposition websites have been blocked since the vote, making it hard for the opposition leaders to communicate with the public.